Add optional --prompt-file <path> argument to start-case-experiment-helper.cjs
that allows supplying an alternative reconstruction prompt file while
preserving the production JSON generation schema.
Requirements implemented:
- Reads UTF-8 prompt file (absolute path or relative to prompts/)
- Replaces {{SCENARIO}} placeholder with scenario text using existing convention
- Validates file exists and contains required placeholder
- Rejects --prompt-file with non-A conditions via clear error
- Only compatible with condition A (production structured-output contract)
- Zero production code changes; apparatus-only modification
- Preserves existing behavior for all conditions B-E without flag
- Does not activate schema variants or freeform handling
Verified: syntax check passes, no whitespace errors in diff.
robbond
8530d954a0